On Spore-cases in Coals. 95 



duced spore-cases similar to those in question, even though the 

 observation of Goldenberg as to their fruit can be rehed on ; the 

 accuracy of which, however, I am inchned to doubt. 



On the whole, then, while giving due credit to Prof. Huxley and 

 those who have preceded him in this matter, for directing attention 

 to this curious and no doubt important constituent of mineral fuel, 

 and admitting that I may possibly have given too little attention to 

 it, I must maintain that sporangite beds are exceptional among 

 coals, and that cortical and woody matters are the most abundant 

 ingredients in all the ordinary kinds ; and to this I cannot think 

 that the coals of England constitute an exception. 



It is to be observed, in conclusion, that the spore-cases of plants, 

 in their indestructibility and richly carbonaceous character, only 

 partake of qualities common to most suberous and epidermal matters, 

 as I have explained in the publications already referred to. Such 

 epidermal and cortical substances are extremely rich in carbon and 

 hydrogen, in this resembling bituminous coal. They are also very 

 little liable to decay, and they resist more than other vegetable mat- 

 ters aqueous infiltration ; properties which have caused them to remain 

 unchanged and to resist the penetration of mineral substances more 

 than other vegetable tissues. These qualities are well seen in the 

 bark of our American white birch. It is no wonder that materials 

 of this kind should constitute considerable portions of such vegetable 

 accumulations as the beds of coal, and that when present in large 

 proportion they should aiford richly bituminous beds. All this agrees 

 with the fact, apparent on examination of the common coal, that the 

 greater number of its purest layers consist of the flattened bark of 

 8igill arias and similar trees, just as any single flattened trunk im- 

 bedded in shale becomes a layer of pure coal. It also agrees with 

 the fact that other layers of coal, and also the cannels and earthy 

 bitumens appear, under the microscope, to consist of finely com- 

 minuted particles, principally of epidermal tissues, not only from the 

 fruits and spore-cases of plants, but also from their leaves and stems. 

 The same considerations impress us, just as much as the abundance 

 of spore-cases, with the immense amount of the vegetable matter 

 which has perished during the accumulation of coal, in comparison 

 with that which has been preserved. 



I am indebted to Dr. T. Sterry Hunt for the following very 

 valuable information, which at once places in a clear and precise light 

 the chemical relations of epidermal tissue and spores with coal. 

 Dr. Hunt says : — ^" The outer bark of the Cork-tree and the cuticle of 

 many if not all other plants consists of a highly carbonaceous matter, 

 to which the name of suherin has been given. The spores of Lyco- 

 podium also approach to this substance in composition, as will be 

 seen by the following, one of two analyses by Duconi,* along with 



* Liebig and Kopp, Jahresbucli, 1847-48. 



